A head-mounted display device (HMD) worn on the head of a user provides the user with a virtual reality (VR) world. Recently, applications have been introduced which allow the user to play games while watching the screen displayed on the HMD. Existing non-portable display devices such as TV sets let the user's visual field range stray outside the screen. This may prevent the user from concentrating on the screen or having the sense of immersion in the ongoing game. In contrast, wearing the HMD allows the user to watch only images displayed on the HMD. This enhances the sense of immersion in the game and also boosts the sense of entertainment for the user. When the HMD is provided with a head tracking function that updates the display screen in keeping with the attitude of the user's head, the sense of immersion in the visual word is further enhanced.
Recent years have witnessed widespread use of an omnidirectional camera (omniazimuth camera) for capturing an omnidirectional, 360-degree panoramic image. Also, development has been underway of remotely controllable unmanned flying objects. Mounting multiple cameras on such a flying object makes it possible to capture an omnidirectional panoramic image from the air. If the HMD is caused to display the omnidirectional panoramic image captured in this manner and to let the head tracking function update the display screen in keeping with the attitude of the user's head, the user is expected to feel as if he or she is in the real world.